1. Technical Field
The present invention relates to an arrangement with a scale fastened on a support.
2. Background Information
For measuring the relative position of two machine elements, it is required to fasten a scale on one of the machine elements, and fasten a scanning unit on the other one of the machine elements, which can be moved relative to each other. During position measurement, a measuring graduation of the scale is scanned by a scanning unit and position-dependent scanning signals are generated.
In accordance with EP 0 264 801 B1, a scale is mounted on a support and is supported on spheres. The spheres are seated so that they can roll within small ranges. A holding force between the scale and the support is introduced by springs.
By combination of the sphere and spring, fastening and support is only possible in the edge area of the scale, because no planar seating can be achieved within the actual measuring range of the scale.
Scale fastening by optical contact is explained in EP 1 783 463 A1. The contact surface in EP 1 783 463 A1 is divided into a plurality of small contact faces that are spaced apart from each other. The contact faces are embodied in the form of one-piece elements on the scale or on the support. Although secure fastening and a relatively even support of a scale within the measuring range is achieved by this embodiment it is difficult to obtain a stress-free contact force that is homogeneous over the entire measurement graduation level.